The Hopeful Hacker Wireless Networking

 

Home

    Tech Basics

    Boot Camp

    Computer Programs

    From Program to Process

    Passwords

    API

    Wireless Networking 

    Free Email

    Linux

Related Links

Hawking

Netgear

D-Link

Linksys

Intel 

Wireless for Linux

Hopeful Hacker Blog

Other Sites

 Brain Dump

Why Wireless? 

The easier it is to get information, the more useful it is.  That's why wireless networks are so popular.  You don't have to plug in a wire and you're not tethered to anything.  When it works, you just turn on your computer, it connects to the network and you're off.

Wireless networking just like wired networking; wired networks send the information across wires, wireless networks send it over radio waves.  It's the same general process as moving from wired telephones to wireless mobile phones.

With a little luck, wireless networking can be as easy as plugging in a couple of cables.  I've actually had that happen: hooked up a router and has my computer connect to the Internet before I could get back around the desk.

To set up a real wireless network -- computers connected to other computers and all of them connected to the Internet -- usually means running some software, but it can be amazingly fast and easy.

Before you waste your time reading this, here's a hint: the easiest way to set up a network is to buy a complete system.  Most manufacturers sell systems that come with the router, a wireless card for your desktop and/or a card (PCMCIA or USB) for your laptop.  The directions will help you hook it all up and they should all work together right away.  If something goes wrong, you can call a single help line. 

Of course that won't work if you want to use the wireless card built into your laptop, or connect at the coffee shop, or already have an older router installed and don't want to waste it. 

For those situations, a little background can come in handy.

Standards

What makes wireless netwokring easy is the standards.  Rather than every company coming up with its own system, they get together and develop a single system so all of their products can connect to each other.  

It's not a scream, it's an institute 

They do it through a group called the Institute of Electrical and Electronics Engineers (IEEE).  IEEE comes up with standards like 80211(b).  Marketers turn them into consumer products like WiFi.  (IEEE doesn't just work on wireless networks.  It sets standards for everything from power plants to public address systems).

No burning bridges

But it's wireless networks that we're talking about, so back to that.  There's a growing series of wireless networking standards.  From our point of view, they include a few key features.  Backwards compatibility is an important one.  If a system is backward compatible it means that the new model will work with the old model.  

Microsoft has always been big on backwards compatibility when it comes to software.  If you bought a program to use on Windows98, chances are good that it works fine on Windows XP.  It's because the Windows operating systems are generally backwards compatible.  It's convenient, but not without complications -- usually in the form of a lot of extra bagage that builds up as new features are added, and support for old ones sticks around.

For wireless networking, it means that your new laptop that comes with 802.11(g) will still work with 802.11(b) router you have in your home.   It also means that the card in your laptop will link you to the Internet at a coffee shop, even if you're a generation apart.

Right now, the widely used wireless standards are:

Wireless-A    802.11a 

Wireless-B    802.11b

Wireless-G    802.11g  (that's what you get for guessing ahead)

Wireless-N    802.11n    OK, n isn't really a standard yet; IEEE is still hashing out the details.  But it's on store shelves and people are buying it, so we might as well talk about it.

Key Features

So what's the difference (besides the little letter at the end)?   Technically, who the heck knows?  It's a jumble of jargon that only geeks understand (and I think a lot of them are just pretending to get it).   

In the real world (meaning your home, your coffee shop and the airport) the differences come down to some key features:

  • Coverage (how far can your computer be from the router?)
  • Speed (how long does it take to transfer a file?)
  • Security (how easy is it for someone to hack into your system?)
  • Frequency (on what frequency does the system transmit and receive?)

 Which has what

Here's a little chart showing which standards have what key features:

Standard

Frequency

Speed

Coverage

802.11a

5 GHz

54 Mbps

75’

802.11b

2.4GHz

11 Mbps

125’

802.11g

2.4GHz

54 Mbps

125’

802.11n

2.4 GHz

200 Mbps

200’

 

A couple of quick notes:

  • I'm not using the IEEE standards for speed and coverage.  I'm using a rough average of what companies claim
  • Since there's no standard for N yet, the speed and coverage information for N are even more unreliable than the rest.  Coverage is especially dicey.  Most companies aren't even claiming a specific distance, they're using phrases like "200 times better than G." and and "800% increase over G."  Do they mean distance?  Area covered?  In a typical home?  Out at sea?  In their dreams? We'll have to wait, and probably test to know for sure.
  • They use small print, why shouldn't I? 

 

The Devilish Details

So what does it all mean?  Let's take the features one at a time.

Coverage

This is pretty important.  If you buy a wireless network system so you can work on your deck and the signal doesn't reach that far, it sucks.  

For the most part, coverage considerations are the same as they are for any radio system.  Your cordless phone stops working if you walk too far from the base.  You lose radio stations if you drive through a tunnel.  Signals get weird when you're under power lines.  And radios don't work at all if you're sealed inside a tin can.  

Keep all of that in mind when the box says a system works up to 150 feet.  That usually means a clear, line-of-sight, 150 feet without any interference.  

A wall in the way drops the distance.  A cordless phone can interfere with the signal.  The type of antenna you're using (on the router and on the computer) can increase or decrease the distance.  And that's just the normal stuff.  Sunspots can screw up everything.  

Until you set up the system, you won't really know how well the signal will travel to where you want to work.  If it doesn't quite reach, you're not necessarily out of luck.  A different antenna, moving the base a bit, or buying a relay might fix it

One irritating thing about wireless networking equipment is the way manufacturers avoid talking about the power.  If you're ever used walkie-talkies you know that 5 watt systems travel farther than 1 watt systems.  Knowing the power is, well, empowering.  But wireless hardware makers don't talk about it much.

Part of the problem is that when you talk about watts people often ask "what?"  So companies started dropping the details about actual power and just giving the estimated distance a system will cover.  That can be handy, but it makes it hard to really compare the raw ability of two systems.  Terms like "superpower," "ultradistance" and "xpd2100" are catchy, but don't reveal much useful information.

If you really want to compare systems, and get the best performance, here's what to look for:

Power

look at the technical spec sheet, poke around on the internet or call the manufacturer.  Someone knows how powerful the transmitter is (measured in watts).  Keep in mind that your base transmits to your computer and your computer has to transmit back to your base.  To network, the signals have to go back and forth.  Using more power one way won't help much, so the router you buy and the card in your computer should be roughly the same strength.

Antenna

This is an important part of the system.  The right antenna in the right place can make a big difference in the coverage you get.  And when it comes to receiving a signal, improving the antenna is about your only option for increasing range.

And the antenna is often overlooked.  Why?  Because antennas can be irritating.  They get in the way, stick up and detract from the overall sleek look of your laptop.  For convenience and beauty, laptop makers often hide the antenna somewhere inside the computer.  That can limit your range.  The best way around this problem is to buy a separate wireless card for your computer, preferable with an external antenna jack so you can experiment with different configurations.

As far as antenna design, there's really only one factor that affects range -- and it involves a tradeoff.  A good way to think about it is to compare it to yelling.  If you open your mouth and shout, your voice will cover a reasonably wide area, but may not travel too far.  If you cup your hands around your mouth, your voice will travel farther, but along a narrorer path.

This is how antennas work.  The most basic antenna is called omnidirectional.  That's supposed to mean that it transmits and receives signals equally well in all directions.  It's a bit of a misnomer because the standard omnidirectional antenna -- a wire sticking straight up -- transmits and receives equally well 360 degrees perpendicular to the wire, but not very well straight up or straight down.  

For a radio station, that's not too important.  It's not trying to reach listeners in space or listeners underground.  For your network, it can make a difference.  

If your router is in the basement and you work in the attic, you might be directly above the antenna.  You could tilt the antenna so it's parallel to the floor.  That would help you in the attic, but might hurt someone working in the backyard.  Some routers come with two omnidirectional antennas to work around this issue.

If you want to increase range, you have to trade out the omnidirectional antenna with a directional antenna.  Directional antennas work better in one direction, but at the cost of working worse in all of the other directions.  Different designs can increase range, but along a narrower path.  If what you want is to get from the router in your house to the office in your garage, a directional antenna is idea.  

As far as antennas that "kick" is signal farther.  Be careful.  It may be a marketing metaphor for some real advantage, but it could also be pure nonsense.

Speed

Speed doesn't mean the speed of the signal.  All radio signals travel at the speed of light.  No faster and no slower.  In this case, speed really means how fast it can exchange how much information.  It's more a measure of the system's capacity.  It's called speed, because what we're really looking for is the ability to transfer a file of a certain size.  If you want to send a 1 MB picture, a faster network will get the job done sooner.  Not because the signal travels faster, but because it can carry more megabytes at the same time.  

This is a really important point.  The speed of your network tells you how fast information will travel around your network, not how fast information will travel from your network to the Internet.  DSL connects you to the Internet at up to 10 Mbps.  Cable boasts a top speed of about 30 Mbps.  Both are usually a lot slower in practice, but no matter: if you use your network primarily for browsing the net, a 54 Mbps Wireless G system outstrips both DSL and Cable.  Not much point in upgrading your network, because the bottleneck is your link to the Internet.

On the other hand, if you use your network to transfer big files, or stream a TV signal, you might want a higher speed than G can give you.

Incidentally, the greater "speed" of Wireless-N really illustrates how speed is really a function of capacity.  Wireless-N moves files faster by doing more work at the same time.  Previous standards used a single signal or channel to carry information.  N opens up two or four channels so more information can move at the same time.  Imagine a four-lane highway compared to a two-lane highway.

A final note about speed: For networking it's usually measured in megabits per second, shortened to Mbps.  Sometimes you'll see MBps.  The "B" is capitalized, if you didn't notice.  This could be a typo but, if it's not, it stands for megabytes per second.  Bits and bytes are units of digital information.  A byte is 8 bits.  So if the abbreviations are being used correctly, you can compare them by dividing the MBps by 8 to get Mbps.  Or multiplying the Mbps by 8 to get MBps.

Security 

Touchy subject.  A good rule of thumb is that, if you're using a wireless network, somebody -- probably anybody -- can see everything you're doing.  WEP and WPA offer a bit of security, but also a bit of false security.  By all means use them, but also assume they protect you only from accidental intrusions -- like a neighbor with a network that overlaps with yours.  Security standards are a different subject, but the system you choose can help protect you.  If you use the other factors to limit your coverage area to inside the walls of your house, that helps because you'll probably notice a stranger with a laptop in your kitchen.  A directional antenna can also help you keep your signal to where you want it and limit other people's ability to detect it.  
If you're worried about security, don't use a wireless network.  Use wires.  Then someone has to physically hook up to your network to get in.  Of course they could come in through the Internet; that's what firewalls are for.

Frequency

When it comes to choosing among the widely available wireless networks, frequency doesn't make a big difference.  They all operate on 5 GHz or 2.4 GHz and neither offers a big raw advantage.  One consideration, though, is interference.  Cordless phones and other appliances share the 2.4GHz band and can interfere with your wireless network.  If that's a problem, Wireless-A puts you on the less-used 5GHz band.  It's as fast as the others, but the range is only about half that of B & G.  Of course, for security, that might be advantage.

The big downside to A's different frequency is compatibility.  Some cards cover both the 2.4GHz and 5GHz bands and work with all of the current standards, but they're not common.  If you just have A you won't be able to tap into the WiFi at a coffee shop, library or airport.